11821821 has 24 divisors (see below), whose sum is σ = 17939040. Its totient is φ = 6911520.

The previous prime is 11821787. The next prime is 11821841. The reversal of 11821821 is 12812811.

It is a de Polignac number, because none of the positive numbers 2^k-11821821 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 11821791 and 11821800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11821841) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9966 + ... + 11088.

It is an arithmetic number, because the mean of its divisors is an integer number (747460).

Almost surely, 2^11821821 is an apocalyptic number.

11821821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

11821821 is a deficient number, since it is larger than the sum of its proper divisors (6117219).

11821821 is a wasteful number, since it uses less digits than its factorization.

11821821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1177 (or 1166 counting only the distinct ones).

The product of its digits is 256, while the sum is 24.

The square root of 11821821 is about 3438.2875097932. The cubic root of 11821821 is about 227.8040598840.

It can be divided in two parts, 1182 and 1821, that added together give a palindrome (3003).

The spelling of 11821821 in words is "eleven million, eight hundred twenty-one thousand, eight hundred twenty-one".